Your explanation is spot on. My one-line take on it is that a larger percentage jobs are AGI-hard than most people are assuming. Take driving for example.

I also think that a lot of people are underestimating how difficult most jobs are, even when it's a job that can be described as "just looking at a spreadsheet".

I'm not so sure. 28 million programmers in the world means 0.3% of all people on earth could be affected by job displacement, but only a small percentage of that 0.3% might lose their job, and the work that's being automated won't result in many visible changes except the financial outlook of companies that previously employed those workers. The programming abilities of LLMs like GPT-4 needs to exceed human ability in a general way before the effects to society could be described as massive.

Of all the hypothetical scenarios for GPT-4, this result represents what the more grounded predictions on the lower end of the hype scale look like. What I am hyped about is the quality of answers/responses, but there's not enough evidence from those leaks for me to know how excited we should be.

That rumor came from Connor Leahy, CEO of Conjecture, https://twitter.com/npcollapse/ . He is a serious person in the AI/ML world and has direct connections to Sam Altman and other big names, so it would be very unusual if the rumor was not true. When trying to interpret that rumor though, you have to realize that being able to "code an entire program" can place GPT-4 somewhere on a scale between high school programmer who can write a basic crud all the way to John Carmack, which actually doesn't tell us very much.